When you go to the gym, you may see a chart on the equipment or on the wall that indicates the recommended “Fat Burning Zone” for your age group, usually representing a range from 60-70% of your maximum heart rate. There are a couple problems with this approach.
One problem is that this zone is usually based on your predicted maximum heart rate for your age, using the formula HRmax = 220 - Age. Your actual HRmax may be quite different from the value predicted. To find your HRmax, you have to actually measure it, using a heart rate monitor.
The other problem is that while you burn a greater percentage of fat in lower levels of exertion like the 60-70% HRmax range, you actually burn fewer total calories per minute of exercise. Simply put, the faster you run and the higher your heart rate, the more calories you will burn per minute.
There is a limit to this approach, however. You can’t sustain running at high speeds for very long, so the total amount of calories burned may not be as great for a short, fast workout as it would be for a workout at a moderately fast pace that you can sustain for a longer period. You also may not be able to run a fast paced workout every day without getting overtired or risking injury.
So, what’s the right pace to run at to maximize the total amount of calories you burn? A recent paper published by the American College of Sports Medicine reports that athletes who exercised for 45 minutes at about 72% of their VO2max (about 83% of their HRmax), burned 519 calories during their workout, but also burned an extra 190 calories in the 14 hour period after their workout was done.
If you are training for a marathon, it is important to do some long runs at slower paces and lower percentages of HRmax to increase your body’s ability to burn fat efficiently. For the rest of us, the best pace to run at to maximize the total amount of calories that your burn is between 75-85% of your HRmax, which is usually labeled as the “Cardio Zone” on the charts at the gym and much higher than the 60-70% zone normally recommended for fat burning.
If you are looking to burn more total calories and lose weight, try increasing the pace of your workouts. You should start to see better results.
What % of your HRmax do you do your workouts at? Tell me in the comments.